1. Field of the Invention
The present invention relates to the field of beaming of elastomeric yarn by unwinding the yarn from cakes in a creel and winding, or beaming, the elastomeric yarn onto a beam in a beaming apparatus.
2. Description of the Related Art
Elastomeric yarn is made by spinning yarn and winding the spun yarn onto a tube to form a cake of elastomeric yarn. Manufacturers of fabrics that include elastomeric yarn require a large number of ends of yarn in order use the yarn in machines to make a fabric, and therefore it is necessary to wind, or warp, a large number of ends from cakes onto a beam to knit or weave the elastomeric yarn into warp-stretch fabrics.
Machines for warping elastomeric yarn are known in the art. Turning to FIG. 1, there is shown a conventional beaming apparatus 11 that include a creel 13, a pre-stretch unit 15, and a warper head 17. Elastomeric yarn is unwound from a large number of cakes 19 in creel 13 where pre-stretch unit 15 produces the pulling force necessary to unwind the yarn from the cakes. The yarn is wound onto a beam in warper head 17.
Creel 13 includes a plurality of cakes, usually from 1000 to 1600. As shown in FIG. 2, cakes 19 have a central core, or tube, 21 around which elastomeric yarn 23 is wound. Typically, creel 13 includes at least one frame with cakes 19 mounted on each frame in long horizontal or vertical rows and in a number of levels or stories above one another. Creel 13 often includes more than one frame in which case the frames are spaced apart either parallel to each other or in some other configuration. Each cake 19 is mounted on a rotatable spool or drive roll and the outer circumferential surface of cake 19, that is, elastomeric yarn 23, is placed in contact with a drive roll 25 that drives the surface of cake 19 in a speed ratio of 1:1 to unwind cake 19. While being unwound, yarn 23 is also subject to a pulling force from pre-stretch unit 15.
Pre-stretch unit 15 includes rolls 27 which pull yarn 23 from creel 13 at a pulling force necessary to assure optimal unwinding of yarn 23. If the pulling force is too high or too low, yarn 23 will unwind incorrectly.
Yarn 23, as it is unwound, typically passes through a thread guide 31 which orients yarn 23 approximately 90 degrees toward pre-stretch unit 15. Thread guide 31 is generally in the shape of a loop called a pigtail, and is made from ceramic.
As yarn 23 exits creel 13, unwound yarn 23 from one level or row of cakes 19 passes through a front guide 33 to orient yarns 23 into a thread sheet. As the threadsheet enters pre-stretch unit 15, yarn 23 is aligned by a separation comb 35 before passing onto rollers 27.
Yarn 23 passes from pre-stretch unit 15 through a reed 37 and then to beam 29. Reed 37 is a comb-like structure that has a base and a plurality of needles connected to the base so as to define spaces therebetween through which the each of yarns 23 from creel 13 are threaded.
A conventional beaming apparatus as described above typically operates at unwinding speeds of about 170 meters per minute, depending on the yarn. As will be explained in greater detail below, there are inherent problems with such conventional beaming apparatuses which are solved by the present invention.